Parallel-ruler.



Q IN E a i 3 Em N m C. C. PFEIFFER.

PARALLEL RULER.

APPLICATION FILED Nov.2s,1913.

Patented June 1, 1915.

Mlnvenor:

HE NORRIS PETERS (20., PHOTO-L/THO" WASHINGTON, D. C

rent in.

CHARLES C. PFEIFFER, OF HOBOKEN, NEW JERSEY, ASSIG-NOR TO KEUFFEL &, ESSER COMPANY, OF I-IOIBOKEN, NEW JERSEY, A CORPORATION OF NEW JERSEY.

PARALLEL-RULER.

Specification of Letters Patent.

Patented June 1, 1915.

Application filed November 25, 1913. Serial No. 802,913.

T all whom it may concern Be it known that I, CHARLES C. PFEIFFER, a citizen of the United States, residing at Hoboken, in the county of Hudson and State of New Jersey, have invented certain new and useful Improvements in Parallel-Rulers, of which the following is a specification.

This invention relates to parallel rulers, and its novelty consists in the construction and adaptation of the parts. I

It is needless to say that the different longitudinal members of a parallel ruler should be strictly parallel and yet, owing to the limitations upon the accuracy of machinery and workman, it is quite difiicult to secure an as semblage of the parts so as to be certain of the parallel alinement of the edges of the members. For instance, when the holes are drilled for the link pivots the ordinary vibration of the drilling tool may, and often does, cause the pivot to assume a slightly inaccurate position, and when such an error is possibly repeated in the drilling of the other holes the result is a slight but nevertheless constant inaccuracy in the ruler.

The object of my invention is to overcome this disadvantage, and I do so by providing at one or more of the pivot centers means for adjusting their position and then fixing it after such adjustment. The result is a provision of means which is simple and economical and which also may be used to correct inaccuracies arising after the instrument has been in use as, for instance, a slight warping of the ruler members, or when the pivot centers become worn more in one spot than in another.

In the drawings there are illustrated instruments embodying my invention.

Figure 1 is a side view of a parallel ruler having two rulers provided with my invention; Fig. 2 is a transverse section on the plane of the line 2-2 in Fig. 1; Fig. 3 1s a similar section, the washer or positioning plate being omitted; Fig. 1 is a view of the ruler beneath the adjustable pivot, and Fig. 5 is a side view of a parallel ruler having three rules provided with my invention.

In the drawings, 10 is one ruler, 11 is another, 12 and 13 are the usual oblique links secured to the rulers by pivots 14, 14, and 15, 15 are knobs for shifting the separate rulers. One of the pivots 140, however, instead of being riveted at the back as usual is provided with an annular depending socket 16 internally threaded and adapted to receive the threaded body of a screw 18. An oblong hole indicated at 100 is drilled in the body of the ruler from its face to receive this pivot socket and, being made larger than the socket, permits of a relatively large movement of the pivot. A recess 101 is also drilled in the rule from the back to receive the screw and, when desired, a washer or positioning plate 19 is inserted in such hole to afford a large bearing surface for the screw.

In assembling such a ruler the rules 10 and 11 are brought together and, if desired, clamped together. The fixed pivots 14 of the link 12 naturally assume their proper relation and so does the fixed pivot of the link 13. The pivot 140, however, is not fixed, its position depending upon the position necessarily assumed by the link 13 when the rules are parallel. Having been placed in position the screw 18 is inserted and tightened into place. Should the rules get out of ad justment the manipulation is repeated. The purpose of the washer 19 is to provide a larger and more rigid bearing surface for the screw head.

In Fig. 5 there is illustrated a parallel ruler with three rules. These are usually made with three rules 20, 21 and 22 united by parallel oblique links 23, 23 and 24, 24: in pairs with a set of three-legged links, one 25 pivoted to the rule 20, one 26 to the rule 21 and another 27 to the rule 22, and all pivoted together by a common pivot 28. The pivots of the three-legged links are preferably fixed and so also are the pivots 30 and 31 securing one of each pair of links 23 and 2 1 to one of the outer rules, but all the other pivots 25 of the oblique links are preferably of my improved form, each like those above described with threaded sockets and set screws and set in holes in the rules like 100 large enough to afford room for adjustment. In the case of such a rule comprising three members, the middle rule 21 would first be adjustedwith respect to the rule 22 having fixed pivots and the outer rule 20 would then be adjusted with respect to it in the manner previously described.

WVhat I claim is:

A parallel ruler, comprising two rules, links connecting the rules, and pivots securing the links to the rules, one of said rules having an elongated opening and one of the pivots comprising a head to which the link the same time permitting the free pivotal is vpivotally connected, said head engaging movement of the link. s 10 one side of the rule beneath the link with- In testimony whereof I affix my signature out clamping the link and having a socket in presence of two witnesses.

in the elongated opening, and a screw en- CHARLES C. PFEIFFER. gaging the opposite side of the rule and Witnesses:

threaded into the socket, said screw device lVM. O. MILLER,

clamping the head against movement and at RICHARD E. KEATH.

Copies of this patent may be obtained for five cents each, by addressing the-0ommissioner of Patents,

Washington, D. 0. V 

